Method of making rotary switch wipers



June 9, 1953 K. w. GRAYBILL ETAL. 2,641,050

METHOD OF MAKING ROTARY SWITCH WIPERS Original Filed March 15, 1946 2 Sheets-Sheet 1 PIC-3.3

FIG. I'

mvroxs KENNETH RAYBILL anus senszauscu ATTORNEY June 9, 1953 K. W. GRAYBILL ETAL METHOD OF MAKING ROTARY SWITCH WIPERS 2 Sheets-Sheet 2 Original Filed March 15, 1946 FIG.6A FIG.5

FIG.6

INVENTORS. KENNETH W. GRAYBILL HANS SENGEBUSCH ATTORNEY Patented June 9, 1953 METHOD OF MAKING ROTARY SWITCH WIPERS Kenneth W. Graybill, Elmhurst, and Hans Sengebusch, Villa Park, Ill., assignors to Automatic Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Original application March 15, 1946, Serial No. 654,556. Divided and this application January 17, 1948, Serial No. 2,905

1 Claim.

The present invention relates in general to electrical switches and more particularly to rotary switches of the step-by-step type, and is a division of our prior application Serial No. 654,556, filed March 15, 2,522,715.

It is an object of the invention to provide a rotary switch which will operate very reliably at higher speeds than heretofore possible.

Another object is to provide an improved rotary switch which will be simple and economical to construct, but which will be very rugged so that it has a long operating life. A further object is to simplify the assembling of such a switch by reducing the amount of manual adjustment needed to bring the parts thereof into their correct relationship,

In keeping with this last object, it is one feature of the invention to mount all the component parts of the switch upon a one-piece frame, this frame being so formed as to automatically position the bank contacts, wipers, electromagnet and the associated armature in their correct relationship.

A further feature resides in an improved form and method of wiper construction which increases the accuracy with which the wipers are spaced apart from one another to conform with the spacing of different levels of bank contacts in a multi-level switch.

Another feature is the provision, in a reverse drive rotary switch, of a novel relationship between the driving spring and the electromagnet for tensioning same, whereby upon deenergization of the electromagnet the spring is capable of delivering a greater amount of energy to advance the switch wipers.

A further feature resides in the provision of an improved arrangement for positively halting the switch wipers in the correct position at the end of each step.

Other objects and features will be pointed out in the course of the following detailed description of the invention, taken in connection with the accompanying drawings, in which Fig. 1 is a front elevation of the switch according to the invention, certain wipers and bank contacts having been omitted for the sake -of clarity,

Figs. 2 and v3 are side elevations showing opposite sides of the switch,

Fig. 4 is a fragmentary view of the bottom of the switch,

Fig. 5 is an enlarged view of the wiper assembly, Fig. 6 is a cross-sectional view taken along the line 66,of Fig, 5,

1946, now Patent 5 Fig. 6A is a fragmentary cross-sectional view of the wiper assembly showing a modified construction, and

Figs. 7, 7A and 7B are greatly enlarged views of a part of the switch mechanism showing successive positions occupied thereby during movement of the switch.

Referring now more in detail to the drawings, all parts of the switch are mounted upon a onepiece frame Ill which is stamped from sheet steel or other suitable material and formed as shown. A pair of oppositely disposed flanges ll drilled and tapped as at [2 are provided on the frame to facilitate mounting same on any desired support (not shown).

To the left of these flanges (Fig. 2) the frame is arcuate in shape and carries a bank of stationary contacts l3 which are arranged in levels or rows. There are twenty-five contacts in each level, and adjacent levels are separated from one another by insulators l4 and spacers 15. Ten levels are shown, but it will be understood that any desired number may be arranged as illustrated, these being secured to the frame by elongated screws l6 which pass through suitable holes in the frame and corresponding holes in the insulators l4 and spacers [5. As indicated by dotted lines in Fig. 3, the individual contacts are so shaped as to avoid being short-circuited by these screws. Each contact in the bank is provided at its outer end with a flared soldering lug and is disposed along a line radial to the axis of the wiper assembly now to be described.

This assembly includes a stationary spindle or shaft 11 one end of which is rigidly secured to the switch frame by means of a flanged stud IS and a nut 19. As shown in Fig. 6, the stud is threaded on the inside to receive shaft IT and is threaded on the outside to receive nut 19, the latter being tightened down after the stud has been inserted in a slot 2! in the switch frame and centered with respect to bank contacts [3. Mounted on the stationary spindle I! is a rotatable hollow shaft or sleeve member 22 having integral therewith (or rigidly affixed thereto) a toothed ratchet wheel 23. A square nut 20 screwed on the end of spindle ll prevents axial movement of the rotary member. Carried by sleeve 22 but insulated therefrom by a tubular insulator 24 are a series of disc-like wiper-carrying hubs 25, a spacer 26 and a drum 21; these face of each wiper-carrying hub so that the distance along the surface of the tubular insulator 24 from one hub to the adjacent hub is increased, with a corresponding increase in leakage resistance between the two. Each hub also has two oppositely disposed peripheral recesses 32 in which are seated a pair of double-ended wiper blades 33 shaped as illustrated in Fig. 5. These blades are rigidly secured to their associated hubs as by spot welding, and it will be noted that the recesses 32 in which they are seated are slightly deeper than the thickness of the blades themselves so that variations in the thickness of the blades due to ordinary manufacturing tolerances will not affect the spacing of the adjacent ones of the hubs. The importance of this mode of construction will be self-evident since the wipers must be spaced along the shaft with great exactness to coincide with the spacing of the difierent levels of bank contacts. In practice excellent results have been obtained by machining the hubs approximately to the desired thickness, welding the wiper blades thereto and then squeezing or compressing the hubs to exact thickness in a power press.

Returning again to the square nut which prevents axial movement of the rotatable portion of the wiper assembly, this is locked in position on the stationary shaft I? by means of a flat spring member 34 mounted on the contact bank as shown in Figs. 3 and 6. A suitable square opening near the free end of the spring member normally fits over the nut 20 preventing rotation thereof; this also serves to assist in keeping the spindle properly centered with respect to the contacts IS. A bent-over lug 35 at the extreme end of the spring member is provided with an index line 36 which is adapted to register with numbered markings on the drum 2'! in order to facilitate determining the rotary position 00- cupied by the wipers at any time. Application of finger pressure to a second lug 3'! on the spring member will deflect sam as shown by dotted lines in Fig. 6, permitting the entire wiper assembly to be drawn away from the frame and the associated contact bank if nut I9 is loosened slightly.

An alternative mode of construction is shown in Fig. 6A. According to this, no nut is provided on the end of spindle H to prevent axial movement of the hollow shaft 22. Instead, spring 34' is provided with a bushing 20 which it is tensioned to press against the end of the hollow shaft to prevent endwise displacement thereof. As indicated, there is a circular recess in the bushing which is adapted to receive the end of spindle l1 and maintain same centered with respect to the bank contacts. The spring 34' may be deflected in the same way as that in Fig. 6, to free the end of the wiper assembly.

The wipers are moved in steps under control of an electromagnet 4| which is rigidly secured to the switch frame by means of a screw 42. As best seen in Fig. 3, a portion of the frame is bent over to form an L-shaped heel piece for this magnet. Associated with the magnet is pivotal magnetic armature 43 which is supported on the frame by means of a non-magnetic yoke 44 and a bearing pin 45, said yoke being rigidly secured to the heel piece by means of two screws as shown. The armature is provided with an elongated lever arm 46 having at its extreme end a toothed portion 41 adapted to mesh with the teeth on wheel 23.

A heavy compression spring 5|, the two ends stroke.

of which are coiled about a pair of flanges centering studs 52 and 53, urges the lever arm toward wheel 23. The stud 52 is provided with a threaded shank which screws into a tapped hole in an arm 54 on the switch frame; this permits the stud to be advanced or retracted to change the spring tension on arm 46, it being understood that unintended changes in such spring tension are prevented by means of a lock-nut 55 which is tightened down after the tension has been properly adjusted.

Pivotally mounted on the lever arm 46 at a point 56 is a pawl 51 which is urged toward the toothed wheel 23 by a light coiled spring 58. When the electromagnet 4| is energized, it attracts armature 43 against the tension of spring 5|, causing the pawl tip to move over one tooth of wheel 23 and lodge in the next notch, while at the same time the toothed portion 41 of the lever arm moves away from wheel 23. A flat spring 59 secured to the contact bank prevents retrograde movement of the wiper assembly during this operation. Upon the subsequent de-energizaticn of the electromagnet, spring 5| quickly restores lever arm 46 to normal causing pawl 51 to advance the toothed wheel and the associated wipers toward their next contact position. As the rotary member reaches said next position, the toothed portion of the lever arm once more meshes with the teeth of wheel 23 so that the wipers (which now are moving very rapidly) will not be carried beyond that position due to acquired momentum.

The manner in which the toothed portion of the lever arm re-engages the toothed wheel is illustrated quite clearly in Figs. 7, 7A and 7B, which show these elements in three successive positions near the end of the lever arms return A particular tooth on each element is identified by a dot in all three figures, making it easy to understand the relative movement of the two elements. In Fig. 7, the toothed portion 4'! is just outside the path of the teeth on wheel 23 and both are moving in the direction indicated by their respective arrows. Fig. 7A shows how the two sets of teeth clear one another as they begin to mesh, while Fig. 73 illustrates their final position, wherein rotation of wheel 23 is halted by the toothed portion of the lever arm 46.

It will be realized that the pull of the electromagnet 4| upon its armature 43 is not constant throughout the movement of the armature toward the core of the electromagnet. Instead as the armature approaches the core, the attractive force between the two increases at an accelerated rate, the change in this force bearing a nonlinear or exponential relationship to the space displacement of the armature from its starting position. To take the fullest advantage of the increased pull which thus occurs as the arms.- ture nears the end of its stroke, spring 5| is specially designed to have a non-linear force/ displacement characteristic approximating the force/ displacement characteristic of the electromagnet and its associated armature, whereby a greater amount of energy is stored in the spring for a given final displacement of the armature than otherwise would be the case. As a result, an increased amount of energy is available to drive the wipers upon deenergization of the electromagnet, and in practice this has been found to contribute very materially to the speed at which the wipers are stepped.

A pair of divergent brushes 60 is provided for each pair of wiper blades. These are mounted on the contact bank as shown in Figs. 1 and 3 and make electrical contact with their associated wipers in all positions thereof, engaging same as shown in Fig. 5. The armature 43 is provided with a second lever arm 6| which operates a set of auxiliary contacts 62. In the drawings, this contact set is illustrated as a single pair of contacts which are separated upon the energization of the electromagnet, but it will be appreciated that any desired other set of contacts might be employed. A second auxiliary set of contacts 63 are mounted on the contact bank by means of a detachable mounting plate 64; these are operated by a pair of pins 65 rigidly affixed to the drum 2! at two diametrically opposite points thereon. Preferably, pins 65 are so located as to operate the associated contact set when the wipers occupy their home position, as shown in Fig. 3.

Having described the invention, what we believe to be new and desire to protect by Letters Patent is set forth in the following claim.

What is claimed is:

The method of making a wiper structure for an electrical stepping switch which comprises recessing one face of a disc-like hub around its outer edge to form a first recess in said one face, recessing the opposite face of said hub to form a second recess around the outer edge thereof and a third recess around the inner edge thereof in said opposite face, positioning in each of said first and said second recesses a wiper blade whose thickness is less than the depth of said first and second recesses, rigidly securing said blades to said hub in said first and second recesses, applying pressure only to said hub along an axial line thereto to compress only that portion of said opposite face of the hub remaining between said second and third recesses, Without applying pressure to said blades, until the over-all thickness between the opposite faces of said hub reaches a predetermined thickness, and then mounting a plurality of said hub assemblies side by side on a shaft so that the total thickness of the complete assembly is dependent only on the thickness of the hubs and independent of the thickness of the Wiper blades.

KENNETH. W. GRAYBILL.

HANS SENGEBUSCH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 668,389 Richards Feb. 19, 1901 707,505 Elden Aug. 19, 1902 1,212,318 Boomer Jan. 16, 1917 1,246,308 Neubaur Nov. 13, 1917 1,595,107 Lyng Aug. 10, 1926 1,707,175 Platt Mar. 26, 1929 1,731,977 Harrison Oct. 15, 1929 1,768,394 Bracke June 24, 1930 1,796,402 Savin Mar. 17, 1931 1,886,059 Smith Nov. 1, 1932 2,038,405 Beach Apr. 21, 1936 2,096,064 Ross Oct. 19, 1937 2,177,483 Hall Oct. 24, 1939 2,257,643 Paschke Sept. 30, 1941 2,277,443 Livingston Mar. 24, 1942 2,349,378 Malihot May 30, 1944 2,438,959 Bartelheim -4 Apr. 6, 1948 2,522,715 Graybill Sept. 19, 1950 FOREIGN PATENTS Number Country Date 391,072 Great Britain Apr. 20, 1933 

